Rust-inhibiting lubricant



= s be a corporation of P No l poe Phiiadeip, ennsylvc i i.

r Application August 30, 19%, v

l do designer I to Serial No. 551,997

The present invention relates to lubricant compositions, and more particularly to rust-inhibiting lubricants suitable for the lubrication of steam turbines, internal combustion engines, gears, cables, and other metal surfaces exposed to rusting or corroding conditions during use.

The lubricant of the present invention is especially adapted for use in the lubrication of steam turbines, and has proved very satisfactory in inhibiting rust and corrosion of turbine parts, such rusting normally being caused by the steam condensate entrained in the lubricants heretofore employed.

The lubricant of the present invention is not only satisfactory from the view point of rustinhibition, but is likewise substantially unafiected by steam or water and retains a gooddemulsibility value during its use in steam turbines.

'In accordanc with the present invention, there is added to a hydrocarbon oil, such as lubricating oil of suitable viscosity, a small quantity of an oil-soluble reaction product of an alkyl acid phosphat having from 8 to 16 carbon atoms in the alkyl group and a branched-chain alkylamine containing from d to 16 carbon atoms in the alkyl group. Such reaction product is preferably pnepared by bringing equimolar quantities of thereactants to a temperature between 100 F. and 200 F. and efiecting reaction between the components at such temperature. It is believed, although not definitely known, that the reaction produces an addition salt since no byproducts appear to b formed. The reaction. is usually fairly rapid, with the evolution of heat, and the reaction product usually comprises a clear, reddish-brown, viscous oil. It is not necessary in all cases to use exactly euuimolar proportions of the acid phosphate and the amine, since it has been found desirable to have the reaction product slightly on the alkaline side, with a pH of about 8. This is accomplished by employing a slight excess of the amine over that required for complete neutralization of the acid phosphate. While it is preferred to cause direct reaction between the amine and the acid phosphate, such reaction may be carried out by adding the reactants to hydrocarbon oil, and then adjusting the. temperature of the mixture to effect reaction,

' thus producing a hydrocarbon oil solution or the reaction product, which. if desired, may "be further diluted with additional oil.

The alkyl acid phosphates which may be utilined in making up the reaction product are the monoor dialwl acid phosphates having from 8 to 16 carbon atoms in the alkyl group. a

monoand diesters, or ixtures thereohmay be I exemplified by the monoand diphosphoridacld esters of octyl alcohol, .nonyl alcohol, tetradecyl alcohol,

simple monoor diesters or mixtures of monoand diesters, and the alcohols employed in the manufacture of the esters may besingle alcohols or mixtures of such-alcohols of from 8 to lfi-carbon atoms, the alcohols having either s. straightchain or a branched-chain structure.

The branched-chain alkylamines containing from 4 to 1!) carbon atomsjwhich may be used in the production-of the reaction product includeprimary, secondary, and tertiary amines, or mixtures of two or more thereof.- Exemplary of these compounds, all of which are characterized by the presence of branched-chain alkyl groups,

are mono-, di-, and tri-isobutyl amines, tertiary butyl amines, iso-amylamlnes, secondary amylamines, tertiary amylamines, the branched-chain hexylamines, heptylamlnes. octylamines, nonylamines, decylamines, undecylamines, dodecylamines, tridecylamines, tetradecylandnes, pentadecylamines, and hexadecylamines. In general. any alkylamine having a carbon chain of 4; to 10 carbon atoms and at least-one substituent alkyl group of 1 to 4 carbons, constituting in into a branched-chain alkylamine, may be employed.

In preparing the improved lubricant containing the rust-inhibiting reaction product, there also may be added a small quantity of an antioxidant suitable for inhibiting the development of acidity or of sludge in the oil. Various amines or phenolic compounds may be employed. preferably a naphthylamine such as phenyl alpha naphthylamine, although other amines compatible with the rust inhibitor may be used.

The quantity of'rust inhibiting reaction product to be added to the lubricant is usually small and falls within the range of 0.005% to 1%, the we ferred amount being from 0.01% to 0.1% by weight. The antioxidant which may be utilized 0 in conjunction with the rust inhibitor has been found satisfactory in amounts ranging ,from

0.05% to 0.5 by weight. 0.1% to 0.2% bein preferred.

The present invention may be further illus- I trated by the following example, which. however. is not to be construed as limiting the scope thereof.

A mixture of monoand dilauryl acid phosalcohol, decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl pentadecyl alcohol, i and hexadecyl alcohol. The acid esters may be Blank oil"...

the mixture was added di-Z-ethyl hexylamine, the temperature or the mixture being adjusted to about 130 F. The mixture was thoroughly agitated and during the ensuing reaction, the temperature rose to about 200 F. The quantity of amine added was suflicient to bring the pH of the reaction product to about 8, and in the case of these specific reactants, it was found that 1.1 parts by weight of the lauryl acid phosphate required 1 part by weight of di-2-ethyl hexylamine to produce the desired product of pH8, 'the amine being present in slight excess of that required for complete neutralization. The resulting reaction product, which appeared to be an addition salt, consisted of a clear, reddish-brown, viscous oil. This material was added in various percentages, with and without an antioxidant, i. e., phenyl alphanaphthylamine, to a selective solvent refined lubricating oil having an A. P. I. gravityof 32 and a Saybolt universal viscosity of 155 seconds at 100 F. The blank oil and the blends were then tested for rust inhibiting properties in accordance with the A. S. T. M. Method D 665-42T entitled Method of Test for Rust Preventing Characteristics of Steam Turbine Oils in the Presence of Water. Such test comprised essentially immersing a polished steel strip in a beaker containing 300 cc. of oil to be tested, raising the temperature of the oil to 140 F. and stirring for /2 hour, removing 50 cc. of the oil and replacing with 30 cc. of water, continuing the 4 effective for the designated purpose, does not increase the steam emulsion number or the neutralization number beyond permissible limits.

The lubricants of this invention, while especially adapted to the lubrication of steam turbines, are alsosuitable for use in many other mechanisms including internal combustion engines, compressors, gears, and the like.

. I claim:

l. A lubricant comprising hydrocarbon oil and a rust-inhibiting quantity of an oil-soluble reaction product 01 an alkyl acid phosphate having from 8 to 16 carbon atoms in the alkyl group and a branched-chain alkylamine containing from 4 to 16 carbon atoms in the alkyl group.

2. A lubricant comprising hydrocarbon oil, a rust-inhibiting quantity of an oil-soluble reaction product 01 an alkyl acid phosphate having from 8'-to 16 carbon atoms in the alkyl group and a branched-chain alkylamin'e containing i'rom 4 to 16 carbon atoms in the alkyl group, and air amine antioxidant.

3. A lubricant comprising hydrocarbon oil and i from 0.005% to 1.0% by weight or an oil-soluble stirring at 140 F. for 48 hours, removing the steel strip and washing it with naphtha to remove oil, and examining the strip for the percent surface rusted.

The results of the tests with the various oil compositions are given in the following table.

Condition of steel strip 80 Blank oil+0.25% reaction product 0 0 Blank oi l+0.05% reaction product... Blank o1i+0.0l% reaction product Blank oil+0.0l% reaction product-H) antioxidant 3 GOO QOO

! Luuryl acid phosphate-di-2ethyl hexylamine.

' Phcnyl alpha naphthylamine.

As will be seen from the above data, the reaction product is compatible with the oxidation inhibitor, and its rust inhibiting qualities are not destroyed by the washing action of water. Furthermore the presence of the inhibitor, with or without the antioxidant, in the concentrations reaction product of an alkyl acid phosphate having from 8 to 16 carbon atoms in the alkyl group and a branched-chain alkylamine containing from 4 to 16 carbon atoms in the alkylgroup.

4., A lubricant comprising hydrocarbon .oil, from 0.005% to 1.0% by weight of an oil-soluble reaction product of an alkyl acid phosphate having from 8 to 16 carbon atoms in the alkyl group and a branched-chain alkylamine containing 1mm 4 to 16 carbon atoms in the alkyl group, and from 0.05% to 0.5% by weight of an amine antioxidant.

5. A lubricant comprising hydrocarbon oil and a rust-inhibiting quantity of an oil-soluble reaction product of lauryl acid phosphate and (11-2- ethyl hexylamine.

6. A lubricant comprising hydrocarbon oil, a rust-inhibiting quantity or an oil-soluble reaction product of lauryl acid phosphate and di-2-ethyl hexylamine, and an oxidation-inhibiting quantity of a naphthylamine.

7. A lubricant comprising hydrocarbon oil, from 0.005% to 1.0% by weight of an oil-soluble reaction product oi. lauryl acid,phosphate and di-2-ethyl hexylamine, and irom 0.05% to 0.5% by weight of phenyl alpha naphthylamine.

8. A lubricant comprising hydrocarbon oil, about 0.01% by weight of an oil soluble reaction product of lauryl acid phosphate and di-2-ethyl hexylamine, and about 0.1% by weight of phenyl alpha naphthylamine. 

